Test drive with new resonator

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Test drive with new resonator

September 18, 2016, 08:43:04 pm

I took the coach for a drive after installing the Aero AT5050 resonator (muffler, whatever). More growl, more giddyup and good for a grin. It sounded like the old "Mike boats" (landing craft) we used in Micronesia years ago and it was much more responsive to the throttle. I'm looking forward to seeing how it does on the long inclines. We hope to leave for the Northwest and Idaho in the next week or so, so this will give us a good idea about mileage, over heating, etc.

Re: Test drive with new resonator

Reply #1 – September 18, 2016, 10:12:35 pm

Did you gain any boost pressure on the intake side? Maybe 0.5 psi. I guessing that the turbo lag is improved and the soot generation period is reduced. Is the noise level reasonable?

Re: Test drive with new resonator

Reply #2 – September 18, 2016, 10:29:47 pm

Oh BTW a slash tip on the exhaust (45 degree) is way better than a straight tip. You can find these coefficients in ASHRAE for comparison. You can look up your engine exhaust rate on a Donaldson chart pdf online and determine the max exhaust velocity. All science no marketing BS. Not at the office now or I could dig up the evidence.

Re: Test drive with new resonator

Reply #3 – September 18, 2016, 11:41:34 pm

Defintely more fun to drive isn't it? The grin factor is for real.

Is your coach a red top 450 hp?

Looking forward to your report.

Played with mine from ca. across Colorado and Nebraska at different speeds for the last three days and 1,700 miles and got some numbers from my redtop 450.

Re: Test drive with new resonator

Reply #4 – September 19, 2016, 12:17:20 am

Quote from: Caflashbob – September 18, 2016, 11:41:34 pm

Defintely more fun to drive isn't it? The grin factor is for real.

Is your coach a red top 450 hp?

Looking forward to your report.

Played with mine from ca. across Colorado and Nebraska at different speeds for the last three days and 1,700 miles and got some numbers from my redtop 450.

It's a surprise, even after hearing the reports. Yes, it is a 450 ISM. Was not impressed before this.

Re: Test drive with new resonator

Reply #5 – September 19, 2016, 09:37:21 am

After you have a couple hundred miles on your new exhaust system, crawl under there and check all the clamps. You may find some of them have loosened up a little due to heating/cooling cycle, and need to be tightened a bit. After that, they should be good.

Re: Test drive with new resonator

Reply #6 – September 19, 2016, 11:25:14 am

Thsbkfull for the resonator references posted here as it got me started on my quest.

Then the posting about the VPMS gave me the tools necessary to delve into what foretravel built.

The resonator seems to have lowered the back pressure enough to drop the engines temp increases under a heavy load.

At the same time I changed the jammed on high hydraulic fan speed controller that foretravel speced to make the engine run as cool as possible with a quiet muffler.

Both pieces worked together as far as they thought.

The 180 to 199 thermostat change and the lowered back pressure seems to have lower the engines temp rise up steep grades and dropped 40 or more hp lost from the fan loads.

Towing at 70 across the rolling flatlands on I25 to I76 to I80 to Omaha from Pueblo resulted in a 700 mile stretch averaging 10 mpg.

One hundred miles towing at 75mph. Little wind. 9.3 mpg on the RMPG on the VPMS.

Last one hundred fifty miles was at 65.

Until a strong quartering wind came up towards the front right corner I was showing 11.5 mpg. Seriously.

Heavy wind dropped it at the worst to 10 mpg.

Boost at 75 was 10 psi.

Boost at 70 was 7.5 average

Boost at 65 was around 5.

Best RPMG for a low wind short stretch on flat ground at 65mph was 11.7.

Coaches long term Cummins memory for 120k miles shows 7.5 mpg.

My current total mpg since the two installations shows 8.4 mpg.

That includes going to the sequoia's, , local mountains. , Six hours in bumper to bumper traffic in LA, towing at 75mph up hills in New Mexico, wolf creek pass and such.

Passed numerous trucks and such up to the high 70's mph a bunch of times also

Tow is a Solara at 3,600 pounds.

Full water and 2/3rd's plus fuel

Re: Test drive with new resonator

Reply #7 – September 19, 2016, 01:28:57 pm

That's a lot of useful information, Bob. What engine are you running and what is the weight of your RV?

Re: Test drive with new resonator

Reply #8 – September 19, 2016, 01:51:45 pm

Quote from: Caflashbob – September 19, 2016, 11:25:14 am

Boost at 75 was 10 psi. Boost at 70 was 7.5 average Boost at 65 was around 5.

The boost numbers are amazing! The turbo was hardly working. We had both boost and pyrometer gauges in previous coaches and missed them when we got this coach, since I pretty much drove by those readings when climbing. In checking (on this forum), someone told me, unless I "hot rodded" the engine, there was no reason to have them. Hmm, I'd still like to have them, though, where I could mount them would be dicey. $:-\$

Re: Test drive with new resonator

Reply #9 – September 19, 2016, 04:09:30 pm

Quote from: Sven and Kristi – September 19, 2016, 01:28:57 pm

That's a lot of useful information, Bob. What engine are you running and what is the weight of your RV?

Cummins celect plus m11 built in oct 96 at 450hp and 1450 torque. Verified

Full GVW at 32,000 pounds. Plus the 3,600 pound car.

Was a dog compared to countless big engined high line coaches I have driven as a gear head Rv sales manager long ago.

First drive I said SOMETHINGS WRONG. Cummins shop service writer was courteous but had little interest in the details.

Cummins shop Foreman was/is very knowledgeable but this is a finesse thing. Lots of expensive steps and 4 years of incremental improvement and research.

Fixed

Sounds crazy BUT I think on flat ground,no wind, no tow and 60mph that the RMPG will be in the 12's

Re: Test drive with new resonator

Reply #10 – September 19, 2016, 04:20:54 pm

Love the boost gauge. Like you I drive with it. Shows wind loads and grade changes not visible.

Many times I have used a GPS program on my iPhone to verify altitude every so long just to see if I am going up or down hill in reality versus what it LOOKS like.

You can feel the coach pull up to the cruise set point. DW noticed that. Said it not do that before. At part throttle.

Re: Test drive with new resonator

Reply #11 – September 19, 2016, 04:31:50 pm

Pretty amazing fuel figures. My 32000 lb 99 320 never did better than 8.3 mpg on an extended trip with a 2500 lb toad.
Running about 70 mph. Actually mileage increased about .2 mpg with 500 hp upgrade. Kind of makes sense when the
silverleaf shows 50% load on flat ground for the 500 vs 60% load for the 450.
Have had many busses and motorhomes, and have never got near 10 miles per gallon.

Re: Test drive with new resonator

Reply #12 – September 19, 2016, 04:58:50 pm

The fan load I think was a big part of the bad mileage. Cummins shop foreman said the fan on high runs 50hp and heats up the hydraulic oil causing excess hydraulic fan motor wear and seal leaking from the pump and fan drives. Duh. Like alot here have experienced and posted.

Re: Test drive with new resonator

Reply #13 – September 19, 2016, 05:17:25 pm

At the same time I changed the jammed on high hydraulic fan speed controller that foretravel speced to make the engine run as cool as possible with a quiet muffler.

Where do I find this controller??

John

Re: Test drive with new resonator

Reply #14 – September 19, 2016, 05:36:14 pm

It's on every unicoach on the metal radiator piping visible when you lift the engine opening cover.

Has two hydraulic lines attached to it.

Expensive part. $700 range.

Someone posted a picture of the valve here with the hoses to replace a danfoss electric switch in anothef brand with these which are a piloted wax capsule ultra reliable unit.

Foretravel sourced the 180 degree unit from the source down south. Talked to the salesman personally a while ago.

Idle fan speed is 165. Full on at 180.

Rest of industry uses a 185 idle max speed at 199 degree unit.

The restrictive high back pressure muffler Foretravel used to be quiet probably got them to max the fan speed to minimize the frantic phone calls from owners saying "my temp gauge moved. My cars and trucks never move. Why does my coach overheat?"

Had a zillion of the same calls and explained this is ok countless times. And demonstrated it a hundred times in the desert with customers

Re: Test drive with new resonator

Reply #15 – September 19, 2016, 08:33:50 pm

So the lower hydraulic fan speeds are the true MPG booster? 25-30 HP saving would help quite a bit if 200 Hp was required for 65MPH travel........ I still have a hankering to hear that open pipe growl!!! Of course the cooler bedroom is a added plus.
David

Re: Test drive with new resonator

Reply #16 – September 19, 2016, 09:16:28 pm

Quote from: ratbug – September 19, 2016, 08:33:50 pm

So the lower hydraulic fan speeds are the true MPG booster? 25-30 HP saving would help quite a bit if 200 Hp was required for 65MPH travel........ I still have a hankering to hear that open pipe growl!!! Of course the cooler bedroom is a added plus.
David

Others input here may help define exactly what does what. Took me four years.

Should be easier as a lot of members here have done the resonator already.

My old Foretravel habits of helping to improve the coaches I guess has not gone away.

Versus keep it a secret and someday sell the coach for more money? Not my style.

Re: Test drive with new resonator

Reply #17 – September 20, 2016, 11:39:38 pm

I installed a 4" resinator and pipe using as few bends and large radius as physically possible to reduce back pressure. (Did this mostly for the sound but also for power increase). MPG increase is non existent after 2500 miles and I have no pyrometer so can't say anything about cooler EGT but here in the flat lands not a big concern anyway. Considering a 5" straight pipe as turbo spool time is way too slow. I have "enough" power as is, but more is always better and too much is the goal.

Re: Test drive with new resonator

Reply #18 – September 21, 2016, 06:44:40 am

Doc,what's your opinion on the bedroom heat aspect?

Re: Test drive with new resonator

Reply #19 – September 24, 2016, 12:34:13 am

Hey John,
I think it is some cooler but 1500 lbs of 200 degree metal does radiate a lot of heat. Most of it goes up...by some strange coincidence. It is a mod I would do again. Hope that helps.

Re: Test drive with new resonator

Reply #20 – September 24, 2016, 09:10:40 am

I do understand that heat rises, but I have a question.
A lot of posts mention the bedroom heating up from the heat cast off the engine.
Has anyone ever considered adding an electric fan to suck the heat out thru the louvered side? Maybe thematically controlled only when the ignition switch is shut off?
Just wondering.

Re: Test drive with new resonator

Reply #21 – September 24, 2016, 09:59:15 am

Long ago I had foretravel outfit many new ORED's with Hayden automatic trans coolers set in the rear grille of the coaches.

Normally on a on off switch on the dash. Two fans.

Mike Grimes would remember what they were I think. But it was 30 years ago

Re: Test drive with new resonator

Reply #22 – October 02, 2016, 09:37:23 pm

We just fitter resonator then traveled 1800mile to Hwh , I would say it spins up quicker and the bed is cooler.
The huge oil drum muffler retains a lot of heat , that vacated space allows better air flow and cooling.
Happy with change

Re: Test drive with new resonator

Reply #23 – October 03, 2016, 01:34:20 am

Been reported frequently before, but if helps someone decide will repeat...... we think the improvement to BR temp alone worth the change. The heat that had built and been held in the matters, and room, and now is not built there from the engine compartment, is a very real plus. We can now use just the from air when driving and the BR stays comfortable, when arrive easy to cool the little more desired.

Not sure if fans in the engine compartment are or are not equal to the resonator result, but the resonator also helps performance moving from a stop.

I have heard some private conversations though that removing the muffler may be a negative to the overall system but I could not follow the logic as I heard the discussion. Maybe others have reported, discussed, that elsewhere?

Re: Test drive with new resonator

Reply #24 – October 03, 2016, 08:51:58 am

I to have concern.... My thoughts are the turbo spins up quicker, and I would assume faster rpms? But sounds like from previous posts here, the quiet, high restriction muffler was foretravels choice. I just have to believe cummins would have applications for this engine without mufflers....... Can a turbo over-spin? Turn too fast?

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